The purpose of this study is the analysis of the instruments and controls of adenovirus gene expression in lytically infected or in transformed cell cultures. Topics currently under investigation include: (A) processing of early adenovirus RNA. (B) analysis of early gene function. (C) virus gene structure and expression as a function of host cell genetic environment. Besides standard procedures of molecular genetics and biochemistry, techniques such as microinjection of animal cells, electron microscopy and gene cloning in prokaryotic vectors, are used in these studies.